A continuously variable transmission of this kind is constructed with, e.g., clamping a disc-shaped roller between a pair of discs arranged opposed to each other. The portion of the pair of discs where the outer side from a predetermined radius has an arcuate plane congruent with the arc centered on the center point of opposed planes of those discs, and such arcuate plane is leading to circumferential direction. The plane thus incurved three-dimensionally is a toroidal plane. The toroidal plane functions as a rolling face and the roller is clamped therebetween. The roller is a disc-shaped member and its sectional figure along in-depth direction of the outer circumferential portion is congruent with the arcuate figure of the rolling face of the discs. Accordingly, the roller is rotated by means of rotating one of the discs, and the other disc rotates sequentially. Then, the roller is inclined to move the radial position of the contact portion against one of the discs, i.e., the radial position from the center axis of the disc outward, and also to move the radial position of the contact portion against the other disc to inner circumferential side, so that the speed change ratio corresponding to the proportion of the radii of each contact portions is thereby set.
The amount of the torque to be transmitted by the toroidal type continuously variable transmission of this kind is varied in accordance with the load to clamp the rollers by the discs. The bigger so-called clamping force of the discs for clamping the roller becomes, the more the transmittable torque increases pro rata. Also, in the toroidal type continuously variable transmission, transmission of the torque is executed with forming an oil film between the disc and the roller, and with utilizing a sharing force of the oil film. Therefore, the bigger the torque to be transmitted between the disc and the roller is, the bigger the shearing force of the oil film becomes. Accordingly, the amount of heat is increased at the torque transmitting portion.
Generally, a material of above mentioned discs and rollers is a metal, and a treatment to increase surface hardness is applied on those discs and rollers, however, mechanical characteristics of those such as hardness and abrasion resistance is deteriorated if a temperature is risen when it is under operation due to above mentioned heat generation. In this connection, there is provided a device, which is constructed to execute cooling with forming an oil film by means of spraying lubricating oil aggressively to the outer circumferential face of the roller, and feeding the lubricating oil by rotating the roller to the boundary face where the disc and roller are contacted, is disclosed in Japanese Patent Laid-Open 2000-507667 as a prior art. According to the prior art disclosed in the above-mentioned Laid-Open, the oil film may be formed between the roller and the disc with transporting the lubricating oil blown to the outer circumferential face of the roller to the contact portion with the disc, by means of rotating the roller. Accordingly, a plenty of lubricating oil contacts with the outer circumferential face of the roller, and cooling of the contact portion between the roller and the disc may be thereby executed. However, in general, temperature rise becomes problematic when the roller is rotating in high speed. Accordingly, most of the lubricating oil is easy to be scattered immediately due to centrifugal force even if the lubricating oil is blown to the outer circumferential face of the roller, as disclosed in the above-mentioned Laid-Open. Therefore, amount of the lubricating oil to be fed to the disc is not exactly sufficient and so that there is a disadvantage on the torque transmitting capacity to be limited because of insufficient cooling of the disc.
This invention has been made in the view of the aforementioned technical problem, and its object is to provide a toroidal type continuously variable transmission, which has an excellent cooling effect.